1. Field of the Invention
This invention relates to improvements in connecting devices and more particularly, but not by way of limitation, to a wrist pin for the connecting rod and crank arm of a pumping unit, or the like.
2. Description of the Prior Art
The usual wrist pin in use today for connecting the crank shaft of a pumping unit, internal combustion engine, or the like, with the pittman or connecting rod connected with the usual reciprocating arm extends transversely through the crank member for connection with the connecting rod and is secured in place by a lock nut threadedly secured to the outer end of the wrist pin. These crank arms and connecting rods are usually subjected to a great amount of vibration during reciprocation of the associated arm and one problem with wrist pins is the loosening of the locking nut which frequently results in an inadvertent loss of the wrist pin. In addition, the present day wrist pins are normally disposed in a tapered bore, and wear of the wrist pin frequently enlarges the bore in the crank and causes a necessity of replacing the entire crank. Some attempts have been made to overcome this problem, such as shown by the Reeves U.S. Pat. No. 1,827,487, and the Willis et al U.S. Pat. No. 1,634,166. The Keen patent relates to a crank pin for locomotives and is of hollow construction, with the pin being secured in position by a plurality of studs or bolts. The Willis et al patent shows a wrist pin which includes an outer sleeve having an inner sleeve threadedly secured therein, with the crank being engaged between the head members of the two sleeves. These solutions to the problem have certain disadvantages, however, in that they are expensive in construction and installation.